Configuring VPNs in Crypto-Connect Mode

This chapter provides information about configuring IPSec VPNs in crypto-connect mode, one of the two VPN configuration modes supported by the IPSec VPN SPA. For information on the other VPN mode, Virtual Routing and Forwarding (VRF) mode, see Chapter27, “Configuring VPNs in VRF Mode”

Note The procedures in this chapter assume you have familiarity with security configuration concepts, such as VLANs, ISAKMP policies, preshared keys, transform sets, access control lists, and crypto maps. For detailed information on configuring these features, refer to the following Cisco IOS documentation:Cisco IOS Security Configuration Guide, Release 12.2, at this URL:http://www.cisco.com/en/US/docs/ios/12_2/security/configuration/guide/fsecur_c.html

Note The procedures in this section do not provide detailed information on configuring the following Cisco IOS features: IKE policies, preshared key entries, Cisco IOS ACLs, and crypto maps. For detailed information on configuring these features, refer to the following Cisco IOS documentation:Cisco IOS Security Configuration Guide, Release 12.2, at this URL:

Router Outside Ports and Inside Ports

The Fast Ethernet or Gigabit Ethernet ports on the Cisco 7600 series router that connect to the WAN routers are referred to as router outside ports. These ports connect the LAN to the Internet or to remote sites. Cryptographic policies are applied to the router outside ports.

The Fast Ethernet or Gigabit Ethernet ports on the Cisco 7600 series router that connect to the LAN are referred to as router inside ports.

The IPSec VPN SPA sends encrypted packets to the router outside ports and decrypted packets to the Policy Feature Card (PFC) for Layer 3 forwarding to the router inside ports.

IPSec VPN SPA Outside Port and Inside Port

The IPSec VPN SPA appears to the CLI as a SPA with two Gigabit Ethernet ports. The IPSec VPN SPA has no external connectors; the Gigabit Ethernet ports connect the IPSec VPN SPA to the router backplane and Switch Fabric Module (SFM) (if installed).

One Gigabit Ethernet port handles all the traffic going to and coming from the router outside ports. This port is referred to as the IPSec VPN SPA outside port. The other Gigabit Ethernet port handles all traffic going to and coming from the LAN or router inside ports. This port is referred to as the IPSec VPN SPA inside port.

Port VLAN and Interface VLAN

Your VPN configuration can have one or more router outside ports. To handle the packets from multiple router outside ports, you must direct the packets from multiple router outside ports to the IPSec VPN SPA outside port by placing the router outside ports in a VLAN with the outside port of the IPSec VPN SPA. This VLAN is referred to as the port VLAN. The port VLAN is a Layer 2-only VLAN. You do not configure Layer 3 addresses or features on this VLAN; the packets within the port VLAN are bridged by the PFC.

Before the router can forward the packets using the correct routing table entries, the router needs to know which interface a packet was received on. For each port VLAN, you must create another VLAN so that the packets from every router outside port are presented to the router with the corresponding VLAN ID. This VLAN contains only the IPSec VPN SPA inside port and is referred to as the interface VLAN. The interface VLAN is a Layer 3-only VLAN. You configure the Layer 3 address and Layer 3 features, such as ACLs and the crypto map, to the interface VLAN.

You associate the port VLAN and the interface VLAN together using the crypto engine slot command on the interface VLAN followed by the crypto connect vlan command on the port VLAN. Figure 26-1 shows an example of the port VLAN and interface VLAN configurations.

Figure 26-1 Port VLAN and Interface VLAN Configuration Example

Port VLAN 502 and port VLAN 503 are the port VLANs that are associated with two router outside ports.

You configure the IP address, ACLs, and crypto map that apply to one router outside port on interface VLAN 2. You configure the features that apply to another router outside port on interface VLAN 3.

Packets coming from the WAN through the router outside port belonging to VLAN 502 are directed by the PFC to the IPSec VPN SPA outside port. The IPSec VPN SPA decrypts the packets and changes the VLAN to interface VLAN 2 and then presents the packet to the router through the IPSec VPN SPA inside port. The PFC then routes the packet to the proper destination.

Packets going from the LAN to the outside ports are first routed by the PFC. Based on the route, the PFC routes the packets to one of the interface VLANs and directs the packet to the IPSec VPN SPA inside port. The IPSec VPN SPA applies the cryptographic policies that are configured on the corresponding interface VLAN, encrypts the packet, changes the VLAN ID to the corresponding port VLAN, and sends the packet to the router outside port through the IPSec VPN SPA outside port.

Access Ports, Trunk Ports, and Routed Ports

When you configure VPNs on the IPSec VPN SPA using crypto-connect mode, you attach crypto maps to interface VLANs. Using the crypto connect vlan command, you then attach an interface VLAN either to a Layer 2 port VLAN associated with one or more physical ports, or directly to a physical port. The physical ports can be ATM, POS, serial, or Ethernet ports.

When you crypto-connect an interface VLAN to a port VLAN that is attached to one or more Ethernet ports configured in switchport mode, the Ethernet ports can be configured as either access ports or trunk ports:

Access ports—Access ports are switch ports that have an external or VLAN Trunk Protocol (VTP) VLAN associated with them. You can associate more than one port to a defined VLAN.

Trunk ports—Trunk ports are switch ports that carry many external or VTP VLANs, on which all packets are encapsulated with an 802.1Q header.

When you crypto-connect an interface VLAN to a physical Ethernet port without defining a port VLAN, a hidden port VLAN is automatically created and associated with the port. In this configuration, the Ethernet port is a routed port:

Routed ports—By default, every Ethernet port is a routed port until it is configured as a switch port. A routed port may or may not have an IP address assigned to it, but its configuration does not include the switchport command.

Removing a line in a crypto ACL causes all crypto maps using that ACL to be removed and reattached to the IPSec VPN SPA. This action causes intermittent connectivity problems for all the security associations (SAs) derived from the crypto maps that reference that ACL.

Do not attach a crypto map set to a loopback interface. However, you can maintain an IPSec security association database independent of physical ingress and egress interfaces with the IPSec VPN SPA by entering the crypto map local-address command.

If you apply the same crypto map set to each secure interface and enter the crypto map local-address command with the interface as a loopback interface, you will have a single security association database for the set of secure interfaces. If you do not enter the crypto map local-address command, the number of IKE security associations is equal to the number of interfaces attached.

You can attach the same crypto map to multiple interfaces only if the interfaces are all bound to the same crypto engine.

If you configure a crypto map with an empty ACL (an ACL that is defined but has no lines) and attach the crypto map to an interface, all traffic goes out of the interface in the clear (unencrypted) state.

Do not convert existing crypto-connected port characteristics. When the characteristics of a crypto-connected access port or a routed port change (switch port to routed port or vice versa), the associated crypto connection is deleted.

Do not remove the interface VLAN or port VLAN from the VLAN database. All interface VLANs and port VLANs must be in the VLAN database. When you remove these VLANs from the VLAN database, the running traffic stops.

When you enter the crypto connect vlan command and the interface VLAN or port VLAN is not in the VLAN database, this warning message is displayed:

VLAN id 2 not found in current VLAN database. It may not function correctly unless

VLAN 2 is added to VLAN database.

When replacing a crypto map on an interface, always enter the no crypto map command before reapplying a crypto map on the interface.

Inbound and outbound traffic for the same tunnel must use the same outside interface. Asymmetric routing, in which encrypted traffic uses a different outside interface than decrypted traffic for the same tunnel, is not supported.

After a supervisor engine switchover, the installed SPAs reboot and come back online. During this period, the IPSec VPN SPA’s established security associations (SAs) are temporarily lost and are reconstructed after the SPA comes back online. The reconstruction is through IKE (it is not instantaneous).

Crypto ACLs support only the EQ operator. Other operators, such as GT, LT, and NEQ, are not supported.

Noncontiguous subnets in a crypto ACL, as in the following example, are not supported:

deny ip 10.0.5.0 0.255.0.255 10.0.175.0 0.255.0.255

deny ip 10.0.5.0 0.255.0.255 10.0.176.0 0.255.0.255

ACL counters are not supported for crypto ACLs.

An egress ACL is not applied to packets generated by the route processor. An ingress ACL is not applied to packets destined for the route processor.

Do not apply an IP ACL to the crypto-connect interface or port VLAN. Instead, you can apply IP ACLs to the interface VLAN, as in the following example:

interface GigabitEthernet1/2

! switch outside port

switchport

switchport access vlan 502

switchport mode access

ip access-group TEST_INBOUND in <--- do not apply IP ACL here

!

interface Vlan2

! interface VLAN

ip address 11.0.0.2 255.255.255.0

crypto map testtag

crypto engine slot 4/0

ip access-group TEST_INBOUND in <--- apply IP ACL here

!

interface Vlan502

! port VLAN

no ip address

crypto connect vlan 2

ip access-group TEST_INBOUND in <--- do not apply IP ACL here

!

Note An IP ACL on the interface VLAN will not block inbound encrypted traffic from reaching the VSPA, but can prevent traffic from being routed further after decryption.

In Cisco IOS Release 12.2(33)SXF and earlier releases, IPsec can be configured with manual keying instead of IKE. If you configure manual keying, you must configure SPI to be greater than 4096.

When configuring the IPSec VPN SPA inside and outside ports, follow these guidelines:

Do not change the port characteristics of the IPSec VPN SPA inside or outside port unless it is necessary to set the trusted state. Cisco IOS software configures the ports automatically.

Note Although the default trust state of the inside port is trusted, certain global settings may cause the state to change. To preserve the ToS bytes for VPN traffic in both directions, configure the mls qos trust command on both the inside and outside ports to set the interface to the trusted state. For information on the mls qos trust command, see the “Configuring QoS on the SPA-IPSEC-2G IPSEC VPN SPA” section.

If you accidentally change the inside port characteristics, enter the following commands to return the port characteristics to the defaults:

Router(config-if)# switchport

Router(config-if)# no switchport access vlan

Router(config-if)# switchport trunk allowed vlan 1,1002-1005

Router(config-if)# switchport trunk encapsulation dot1q

Router(config-if)# switchport mode trunk

Router(config-if)# mtu 9216

Router(config-if)# flow control receive on

Router(config-if)# flow control send off

Router(config-if)# span portfast trunk

Do not configure allowed VLANs on the inside trunk port. Cisco IOS software configures the VLAN list on the inside port automatically based on the crypto engine slot command. These VLANs are visible in the port configuration using the show run command.

Do not configure allowed VLANs on the outside trunk port. Cisco IOS software configures these VLANs automatically as hidden VLANs. These VLANs are not visible in the port configuration using the show run command.

Do not remove a VLAN from the IPSec VPN SPA inside port. The running traffic stops when you remove an interface VLAN from the IPSec VPN SPA inside port while the crypto connection to the interface VLAN exists. The crypto connection is not removed and the crypto connect vlancommand still shows up in the show running-config command display. If you enter the write memory command with this running configuration, your startup-configuration file would be misconfigured.

Note It is not possible to remove an interface VLAN from the IPSec VPN SPA inside port while the crypto connection to the interface VLAN exists. You must first remove the crypto connection.

Do not remove a VLAN from the IPSec VPN SPA outside port. The running traffic stops when you remove a port VLAN from the IPSec VPN SPA outside port while the crypto connection to the interface VLAN exists. The crypto connection is not removed and the crypto connect vlan command still shows up in the show running-config command display. Removing a VLAN from the IPSec VPN SPA outside port does not affect anything in the startup-configuration file because the port VLAN is automatically added to the IPSec VPN SPA outside port when the crypto connect vlan command is entered.

Configuring an Access Port

This section describes how to configure the IPSec VPN SPA with an access port connection to the WAN router (see Figure 26-2).

Figure 26-2 Access Port Configuration Example

Note Ethernet ports installed in a Cisco 7600 SIP-400 in the chassis cannot be configured as switch ports.

To configure an access port connection to the WAN router, perform the following task beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# crypto isakmp policy priority

...

Router(config-isakmp) # exit

Defines an ISAKMP policy and enters ISAKMP policy configuration mode.

priority —Identifies the IKE policy and assigns a priority to the policy. Use an integer from 1 to 10000, with 1 being the highest priority and 10000 the lowest.

For details on configuring an ISAKMP policy, see the Cisco IOS Security Configuration Guide.

Step 2

Router(config)# crypto isakmp key keystring address peer-address

Configures a preshared authentication key.

keystring —Preshared key.

peer-address —IP address of the remote peer.

For details on configuring a preshared key, see the Cisco IOS Security Configuration Guide.

Verifying the Access Port Configuration

Configuring a Routed Port

This section describes how to configure the IPSec VPN SPA with a routed port connection to the WAN router (see Figure 26-3).

Note When a routed port without an IP address is crypto-connected to an interface VLAN, a hidden port VLAN is created automatically. This port VLAN is not explicitly configured by the user and does not appear in the running configuration.

Figure 26-3 Routed Port Configuration Example

Routed Port Configuration Guidelines

When configuring a routed port using the IPSec VPN SPA, follow these configuration guidelines:

When a routed port has a crypto connection, IP ACLs cannot be attached to the routed port. Instead, you can apply IP ACLs to the attached interface VLAN.

Unlike an access port or trunk port, the routed port does not use the switchport command in its configuration.

To configure a routed port connection to the WAN router, perform this task beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# crypto isakmp policy priority

...

Router(config-isakmp) # exit

Defines an ISAKMP policy and enters ISAKMP policy configuration mode.

priority —Identifies the IKE policy and assigns a priority to the policy. Use an integer from 1 to 10000, with 1 being the highest priority and 10000 the lowest.

For details on configuring an ISAKMP policy, see the Cisco IOS Security Configuration Guide.

Step 2

Router(config)# crypto isakmp key keystring address peer-address

Configures a preshared authentication key.

keystring —Preshared key.

peer-address —IP address of the remote peer.

For details on configuring a preshared key, see the Cisco IOS Security Configuration Guide.

Configuring a Trunk Port

Caution When you configure an Ethernet port as a trunk port, all the VLANs are allowed on the trunk port by default. This default configuration does not work well with the IPSec VPN SPA and causes network loops. To avoid this problem, you must explicitly specify only the desirable VLANs
.

This section describes how to configure the IPSec VPN SPA with a trunk port connection to the WAN router (see Figure 26-4).

Figure 26-4 Trunk Port Configuration Example

Note Ethernet ports installed in a Cisco 7600 SIP-400 in the chassis cannot be configured as switch ports.

Trunk Port Configuration Guidelines

When configuring a trunk port using the IPSec VPN SPA, follow these configuration guidelines:

When you configure a trunk port for cryptographic connection, do not use the “all VLANs allowed” default. You must explicitly specify all the desirable VLANs using the switchport trunk allowed vlan command.

Due to an incorrect startup configuration or through the default trunk port configuration, an interface VLAN might be associated with a trunk port. When you try to remove the interface VLAN from the VLAN list, you might receive an error message similar to the following:

Command rejected:VLAN 2 is crypto connected to V502.

To remove the interface VLAN from the VLAN list, enter the following commands:

Router# configure terminal

Router(config)# interface g1gabitethernet1/2

Router(config-if)# no switchport mode trunk

Router(config-if)# switchport trunk allowed vlan 1

Router(config-if)# switchport mode trunk

Router(config-if)# switchport trunk allowed vlan 1,502,1002-1005

Note VLANs in the VLAN list must not include any interface VLANs.

To ensure that no interface VLANs are associated when you put an Ethernet port into the trunk mode, enter the following commands in the exact order given:

Router# configure terminal

Router(config)# interface g1gabitethernet1/2

Router(config)# no shut

Router(config-if)# switchport

Router(config-if)# switchport trunk allowed vlan 1

Router(config-if)# switchport trunk encapsulation dot1q

Router(config-if)# switchport mode trunk

Router(config-if)# switchport trunk allowed vlan 1,502,1002-1005

Note VLANs in the VLAN list must not include any interface VLANs.

A common mistake when configuring a trunk port occurs when you use the add option as follows:

Router(config-if)# switchport trunk allowed vlan add 502

If the switchport trunk allowed vlan command has not already been used, the add option does not make VLAN 502 the only allowed VLAN on the trunk port; all VLANs are still allowed after entering the command because all the VLANs are allowed by default. After you use the switchport trunk allowed vlan command to add a VLAN, you can then use the switchport trunk allowed vlan ad d command to add additional VLANs.

To remove unwanted VLANs from a trunk port, use the switchport trunk allowed vlan remove command.

Caution Do not enter the
switchport trunk allowed vlan all command on a secured trunk port. In addition, do not set the IPSec VPN SPA inside and outside ports to “all VLANs allowed.”

To configure a trunk port connection to the WAN router, perform this task beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# crypto isakmp policy priority

...

Router(config-isakmp) # exit

Defines an ISAKMP policy and enters ISAKMP policy configuration mode.

priority —Identifies the IKE policy and assigns a priority to the policy. Use an integer from 1 to 10000, with 1 being the highest priority and 10000 the lowest.

For details on configuring an ISAKMP policy, see the Cisco IOS Security Configuration Guide.

Step 2

Router(config)# crypto isakmp key keystring address peer-address

Configures a preshared authentication key.

keystring —Preshared key.

peer-address —IP address of the remote peer.

For details on configuring a preshared key, see the Cisco IOS Security Configuration Guide.

When configuring a connection to a WAN interface using an IPSec VPN SPA, follow these guidelines and note these restrictions:

To configure an IPSec VPN SPA connection to a WAN interface, make a crypto connection from the WAN subinterface to the interface VLAN as follows:

Router(config)# interface Vlan101

Router(config-if)# ip address 192.168.101.1 255.255.255.0

Router(config-if)# no mop enabled

Router(config-if)# crypto map cwan

Router(config-if)# crypto engine slot 4/0

Router(config)# interface ATM6/0/0.101 point-to-point

Router(config-subif)# pvc 0/101

Router(config-subif)# crypto connect vlan 101

You must configure a crypto connection on subinterfaces for ATM and Frame Relay.

For ATM, there is no SVC support, no RFC-1483 bridging, and no point-to-multipoint support.

For Frame Relay, there is no SVC support, no RFC-1490 bridging, and no point-to-multipoint support.

For Point-to-Point Protocol (PPP) and Multilink PPP (MLPPP), you must make the physical interface passive for routing protocols, as follows:

Router(config)# router ospf 10

Router(config-router)# passive-interface multilink1

For PPP and MLPPP, when the crypto connect vlan command is configured on an interface, an ip unnumbered Null0 command is automatically added to the port configuration to support IPCP negotiation. If you configure a no ip address command on the WAN port in the startup configuration, the no ip address command will be automatically removed in the running configuration so that it does not conflict with the automatic configuration.

For PPP and MLPPP, there is no Bridging Control Protocol (BCP) support.

When enabled on an inside VLAN, OSPF will be configured in broadcast network mode by default, even when a point-to-point interface (such as T1, POS, serial, or ATM) is crypto-connected to the inside VLAN. In addition, if OSPF is configured in point-to-point network mode on the peer router (for example, a transit router with no crypto card), OSPF will not establish full adjacency. In this case, you can manually configure OSPF network point-to-point mode in the inside VLAN:

Understanding GRE Tunneling in Crypto-Connect Mode

Generic Routing Encapsulation (GRE) is a tunneling protocol that can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to routers at remote points over an IP network.

Note The IPSec VPN SPA is able to accelerate packet processing for up to 2048 GRE tunnels per chassis. Any tunnels not taken over by the IPSec VPN SPA, or any tunnels in excess of 2048, are handled in platform hardware or by the route processor. The router supports any number of GRE tunnels, but adding more IPSec VPN SPAs does not increase the 2048 tunnels per-chassis maximum that will be handled by IPSec VPN SPAs. If you configure more than 2048 tunnels per chassis, you could overload the route processor. Monitor the route processor CPU utilization when configuring more than 2048 tunnels per chassis.

Note Beginning with Cisco IOS Release 12.2(18)SXF, the GRE fragmentation behavior of the VPN module is changed to be consistent with the fragmentation behavior of the route processor. If GRE encapsulation is performed by the VPN module, prefragmentation of outbound packets will be based on the IP MTU of the tunnel interface. After GRE encapsulation is performed by the VPN module, depending on the IPSec prefragmentation settings, further fragmentation may occur. The IPSec fragmentation behavior is unchanged in this release, and is based on the IPSec MTU configuration of the egress interface.

Note On the GRE tunnels that are protected with IPsec and static VTI tunnels, the calculation of the IP MTU of the tunnel takes into account the IPsec overhead, in addition to the GRE overhead, and the resultant MTU is configured as the IP MTU of the tunnel.

GRE Tunneling Configuration Guidelines and Restrictions

When configuring point-to-point GRE tunneling in crypto-connect mode using the IPSec VPN SPA, follow these guidelines:

In a Cisco 7600 series router, GRE encapsulation and decapsulation is traditionally performed by the route processor or the supervisor engine hardware. When routing indicates that encapsulated packets for a GRE tunnel will egress through an interface VLAN that is attached to an IPSec VPN SPA inside port, the IPSec VPN SPA attempts to take over the GRE tunnel interface only if the supervisor engine is unable to process the GRE tunnel interface in hardware. If the supervisor engine cannot process the GRE tunnel interface in hardware, the IPSec VPN SPA will determine if it can take over the interface. By seizing the tunnel, the IPSec VPN SPA takes the GRE encapsulation and decapsulation duty from the route processor. No explicit configuration changes are required to use this feature; configure GRE as you normally would. As long as routing sends the GRE-encapsulated packets over an interface VLAN, the IPSec VPN SPA will seize the GRE tunnel.

If the same source address is used for more than one GRE tunnel, the supervisor engine hardware will not take over the tunnel. The IPSec VPN SPA will take over the tunnel if it meets the criteria discussed in the previous bullet item.

Point-to-point GRE with tunnel protection is not supported in crypto-connect mode, but DMVPN is supported.

If routing information changes and the GRE-encapsulated packets no longer egress through an interface VLAN, the IPSec VPN SPA yields the GRE tunnel. After the IPSec VPN SPA yields the tunnel, the route processor resumes encapsulation and decapsulation, which increases CPU utilization on the route processor.

Caution Ensure that your GRE tunnel configuration does not overload the route processor.

A delay of up to 10 seconds occurs between routing changes and the IPSec VPN SPA seizing the GRE tunnel.

The crypto map must only be applied to the interface VLAN and not to the tunnel interface.

The following options are supported on the tunnel interface: ACLs, service policy, TTL, and ToS.

Configuring the GRE Takeover Criteria

You can configure the takeover criteria for Generic Routing Encapsulation (GRE) processing by using the crypto engine gre supervisor or crypto engine gre vpnblade commands. These two commands allow you to specify whether the GRE processing should be done by the supervisor engine hardware or the route processor or the IPSec VPN SPA.

Note The GRE takeover criteria commands are supported only in Cisco IOS Release 12.2(18)SXE5 and later. In releases prior to Cisco IOS Release 12.2SXE1, the crypto-related GRE tunnels are always taken over by the VPN SPA. In Cisco IOS Release 12.2SXE1, the GRE tunnels are taken over by the VPN SPA only if the supervisor engine hardware cannot do the processing.

To configure a router to process GRE using the supervisor engine hardware or the route processor (RP), use the crypto engine gre supervisor command. When this command is specified, GRE processing by the supervisor engine hardware takes precedence over processing by the route processor (unless the tunnels are from duplicate sources); the RP only takes over GRE processing if the supervisor engine hardware cannot do the processing. If this command is configured, duplicate source GREs will be processed by the route processor.

To configure a router to process GRE using the IPSec VPN SPA, use the crypto engine gre vpnblade command. If the IPSec VPN SPA cannot take over the GRE processing, the GRE processing will be handled either by supervisor engine hardware (which has precedence) or the route processor.

Both of these commands can be configured globally or at an individual tunnel.

Individual tunnel configuration takes precedence over the global configuration. For example, when the crypto engine gre supervisor command is configured at the global configuration level, the command will apply to all tunnels except those tunnels that have been configured individually using either a crypto engine gre supervisor command or a crypto engine gre vpnblade command.

At any time, only one of the two commands (crypto engine gre supervisor or crypto engine gre vpnblade) can be configured globally or individually at a tunnel. If either command is already configured, configuring the second command will overwrite the first command, and only the configuration applied by the second command will be used.

GRE Takeover Configuration Guidelines and Restrictions

When configuring GRE takeover on the IPSec VPN SPA, follow these guidelines and restrictions:

For a GRE tunnel to be taken over by the IPSec VPN SPA, it must first satisfy the following criteria:

– The GRE tunnel interface must be up.

– The route to the tunnel destination must go through the IPSec VPN SPA.

– The Address Resolution Protocol (ARP) entry for the next hop must exist.

– The tunnel mode must be GRE.

– The only supported options are tunnel ttl and tunnel tos. If any of the following command options are configured, then the tunnel will not be taken over:

tunnel key

tunnel sequence-datagrams

tunnel checksum

All other options configured are ignored.

If the GRE tunnels have the same source and destination addresses, then the IPSec VPN SPA will, at most, take over only one of them, and the determination of which specific tunnel is taken over is random.

The IPSec VPN SPA will not take over GRE processing if any of the following features are configured on the tunnel interface:

– DMVPN

– NAT

In crypto-connect mode, the IPSec VPN SPA will not take over GRE processing when the interface VLAN has no crypto map attached. The crypto map must be applied to the interface VLAN and not to the tunnel interface.

If the IPSec VPN SPA cannot take over the GRE processing, the GRE processing will be handled either by the supervisor engine hardware (which has precedence) or the route processor.

When neither the crypto engine gre supervisor command nor the crypto engine gre vpnblade command is specified globally or individually for a tunnel, the IPSec VPN SPA will only attempt to take over GRE processing if the following conditions apply:

– The supervisor engine hardware does not take over GRE processing.

– Protocol Independent Multicast (PIM) is configured on the tunnel.

– Multiple tunnels share the same tunnel source interface and more than one tunnel is up. (If only one tunnel is up, the supervisor engine hardware can still perform the GRE processing.)

When a new configuration file is copied to the running configuration, the new configuration will overwrite the old configuration for the crypto engine gre vpnblade and crypto engine gre supervisor commands. If the new configuration does not specify a GRE takeover criteria globally or for an individual tunnel, the existing old configuration will be used.

GRE keepalives are not supported if crypto engine gre vpnblade is configured.

Configuring the GRE Takeover Criteria Globally

To configure the GRE takeover criteria globally (so that it affects all tunnels except those tunnels that have been configured individually using either a crypto engine gre supervisor command or a crypto engine gre vpnblade command), perform this task beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# crypto engine gre supervisor

or

Router(config)# crypto engine gre vpnblade

Configures a router to process GRE using the supervisor engine hardware or the route processor.

Configures a router to process GRE using the IPSec VPN SPA.

Configuring the GRE Takeover Criteria at an Individual Tunnel

To configure the GRE takeover criteria at an individual tunnel (so that it affects only a specific tunnel), perform this task beginning in global configuration mode:

Command

Purpose

Step 1

Router(config)# interface tunnel number

Creates the tunnel interface if it does not exist and enters interface configuration mode.

number —Number of the tunnel interface to be configured.

Step 2

Router(config-if)# crypto engine gre supervisor

or

Router(config-if)# crypto engine gre vpnblade

Configures a router to process GRE using the supervisor engine hardware or the route processor.

Configuring IP Multicast over a GRE Tunnel

IP multicast is a bandwidth-conserving technology that reduces traffic by simultaneously delivering a single stream of information to multiple recipients. GRE is a tunneling protocol developed by Cisco and commonly used with IPSec that encapsulates a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP network.

In some network scenarios, you might want to configure your network to use GRE tunnels to send Protocol Independent Multicast (PIM) and multicast traffic between routers. Typically, this occurs when the multicast source and receiver are separated by an IP cloud that is not configured for IP multicast routing. In such network scenarios, configuring a tunnel across an IP cloud with PIM-enabled transports multicast packets toward the receiver. The configuration of IP multicast over a GRE tunnel using the IPSec VPN SPA involves three key steps:

Configuring single-SPA mode (if supported) for multicast traffic

Configuring multicast globally

Configuring PIM at the tunnel interfaces

IP Multicast over a GRE Tunnel Configuration Guidelines and Restrictions

When configuring IP multicast over a GRE tunnel, follow these guidelines:

When the hw-module slot subslot only command is executed, it automatically resets the Cisco 7600 SSC-400 card and displays the following prompt on the console:

Module n will be reset? Confirm [n]:

The prompt will default to N (no). You must type Y (yes) to activate the reset action.

When in single-SPA mode, if you manually plug in a second SPA, or if you attempt to reset the SPA (by entering a no hw-module subslot shutdown command, for example), a message is displayed on the router console that refers you to the customer documentation.

If PIM is configured, and the GRE tunnel interface satisfies the rest of the tunnel takeover criteria, the GRE processing of the multicast packets will be taken over by the IPSec VPN SPA.

GRE processing of IP multicast packets will be taken over by the IPSec VPN SPA if the GRE tunnel interface satisfies the following tunnel takeover criteria:

– The tunnel is up.

– There are no other tunnels with the same source destination pair.

– The tunnel is not an mGRE tunnel.

– PIM is configured on the tunnel.

– None of the following features are configured on the tunnel: tunnel key, tunnel sequence-datagrams, tunnel checksum, tunnel udlr address-resolution, tunnel udlr receive-only, tunnel udlr send-only, ip proxy-mobile tunnel reverse, or NAT. If any of these options are specified, the IPSec VPN SPA will not seize the GRE tunnel.

When a tunnel is configured for multicast traffic, the crypto engine gre supervisor command should not be applied to the tunnel.

Configuring Single-SPA Mode for IP Multicast Traffic

Before you configure IP multicast on the IPSec VPN SPA, you should change the mode of the Cisco 7600 SSC-400 card to allocate full buffers to the specified subslot using the Before you configure IP multicast on the IPSec VPN SPA, you should change the mode of the Cisco 7600 SSC-400 card to allocate full buffers to the specified subslot using the hw-module slot subslot only command. If this command is not used, the total amount of buffers available is divided between the two subslots on the Cisco 7600 SSC-400 card.

To allocate full buffers to the specified subslot, use the hw-module slot subslot only command as follows:

Router(config)# hw-module slotslotsubslotsubslotonly

slot specifies the slot where the Cisco 7600 SSC-400 card is located.

subslot specifies the subslot where the IPSec VPN SPA is located.

If the hw-module slot subslot only command is not used, the total amount of buffers available is divided between the two subslots on the Cisco 7600 SSC-400 card.

Configuring IP Multicast Globally

You must enable IP multicast routing globally before you can enable PIM on the router interfaces.

Note The following examples use commands at the level of Cisco IOS Release 12.2(33)SRA.

As of Cisco IOS Release 12.2(33)SRA, the crypto engine subslot command used in previous releases has been replaced with the crypto engine slot command (of the form crypto engine slotslot/subslot {inside | outside}). The crypto engine subslot command is no longer supported. When upgrading, ensure that this command has been modified in your start-up configuration to avoid extended maintenance time.

Access Port in Crypto-Connect Mode Configuration Example

This section provides an example of the access port configuration with router 1 shown in Figure 26-2:

Router 1 (Access Port)

!

hostname router-1

!

vlan 2,502

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.1

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.1

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 13.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

switchport

switchport access vlan 502

switchport mode access

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,502,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

interface Vlan2

!interface vlan

ip address 11.0.0.2 255.255.255.0

crypto map testtag

crypto engine slot 4/0

!

interface Vlan502

!port vlan

no ip address

crypto connect vlan 2

!

ip classless

ip route 12.0.0.0 255.0.0.0 11.0.0.1

!

access-list 101 permit ip host 13.0.0.2 host 12.0.0.2

!

end

Router 2 (Access Port)

!

hostname router-2

!

vlan 2,502

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.2

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.2

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 12.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

switchport

switchport access vlan 502

switchport mode access

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,502,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface Vlan2

!interface vlan

ip address 11.0.0.1 255.255.255.0

crypto map testtag

crypto engine slot 4/0

!

interface Vlan502

!port vlan

no ip address

crypto connect vlan 2

!

ip classless

ip route 13.0.0.0 255.0.0.0 11.0.0.2

!

access-list 101 permit ip host 12.0.0.2 host 13.0.0.2

!

end

Routed Port in Crypto-Connect Mode Configuration Example

This section provides an example of the routed port configuration with router 1 shown in Figure 26-3:

Router 1 (Routed Port)

!

hostname router-1

!

vlan 2

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.2

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.2

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 12.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

no ip address

crypto connect vlan 2

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface Vlan2

!interface vlan

ip address 11.0.0.1 255.255.255.0

no mop enabled

crypto map testtag

crypto engine slot 4/0

!

ip classless

ip route 13.0.0.0 255.0.0.0 11.0.0.2

!

access-list 101 permit ip host 12.0.0.2 host 13.0.0.2

!

end

Router 2 (Routed Port)

!

hostname router-2

!

vlan 2

!

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.1

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.1

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 13.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

no ip address

crypto connect vlan 2

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface Vlan2

!interface vlan

ip address 11.0.0.2 255.255.255.0

no mop enabled

crypto map testtag

crypto engine slot 4/0

!

ip classless

ip route 12.0.0.0 255.0.0.0 11.0.0.1

!

access-list 101 permit ip host 13.0.0.2 host 12.0.0.2

!

end

Trunk Port in Crypto-Connect Mode Configuration Example

This section provides an example of the trunk port configuration with router 1 shown in Figure 26-4:

Router 1 (Trunk Port)

!

hostname router-1

!

vlan 2,502

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.2

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.2

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 12.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 502

switchport mode trunk

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,502,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface Vlan2

!interface vlan

ip address 11.0.0.1 255.255.255.0

crypto map testtag

crypto engine slot 4/0

!

interface Vlan 502

!port vlan

no ip address

crypto connect vlan 2

!

ip classless

ip route 13.0.0.0 255.0.0.0 11.0.0.2

!

access-list 101 permit ip host 12.0.0.2 host 13.0.0.2

!

end

Router 2 (Trunk Port)

!

hostname router-2

!

vlan 2,502

!

crypto isakmp policy 1

encr 3des

authentication pre-share

crypto isakmp key 12345 address 11.0.0.1

!

!

crypto ipsec transform-set proposal1 esp-3des esp-md5-hmac

!

crypto map testtag 10 ipsec-isakmp

set peer 11.0.0.1

set transform-set proposal1

match address 101

!

!

interface GigabitEthernet1/1

!switch inside port

ip address 13.0.0.1 255.255.255.0

!

interface GigabitEthernet1/2

!switch outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 502

switchport mode trunk

!

interface GigabitEthernet4/0/1

!IPSec VPN SPA inside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

!

interface GigabitEthernet4/0/2

!IPSec VPN SPA outside port

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,502,1002-1005

switchport mode trunk

mtu 9216

flowcontrol receive on

flowcontrol send off

spanning-tree portfast trunk

interface Vlan2

!interface vlan

ip address 11.0.0.2 255.255.255.0

crypto map testtag

crypto engine slot 4/0

!

interface Vlan502

!port vlan

no ip address

crypto connect vlan 2

!

ip classless

ip route 12.0.0.0 255.0.0.0 11.0.0.1

!

access-list 101 permit ip host 13.0.0.2 host 12.0.0.2

!

end

IPSec VPN SPA Connections to WAN Interfaces Configuration Examples

The following are configuration examples of IPSec VPN SPA connections to WAN interfaces:

Performance on 7600 IPSEC VPN SPA Example

Note Configuration based on Vanilla VRF mode with back-to-back connection (7600 routers and for each chassis one IPSEC-3G SPA). In Figure 26-5, using a single VSPA supports a maximum of 8 Gbps full duplex (4Gbps unidirectional throughput) which includes encryption or decryption achieved.

Figure 26-5 Performance of 7600 with IPSEC-3G

The following example shows the configuration for Single IPSEC-3G SPA:

Note Single VLAN capable of more than 4 Gbps cannot be scaled as mapping needs to be done separately. Two traffic streams for VLANs need to be sent. Each VLAN (100 and 101) will receive 5Gbps and it is not possible to load balance single VLAN flow across the TWO IPSEC-3G SPA.